This invention relates to the field of coverings for insulated pipe. More particularly, this invention relates to metal coverings, commonly called lagging, for insulated pipe bends or turns.
The insulation of pipe and pipelines in industrial, commercial or residential facilities is important for energy conservation, freeze protection, personnel protection, better process control and pipe protection. Normal specifications for the insulation of hot and/or cold piping requires the installation of a calcium silicate, fiberglass, cellular glass, polyurethane, or other similar insulation material, with this insulation being preserved and protected by a metal jacket. To insulate a piece of pipeline, two formed pieces of insulation from 1 to 2 inches or more in thickness, as desired, each covering one-half of the pipe, are wired together and a thin metal jacket is placed over the insulation to protect the insulation from physical abuse and to weatherproof it. The difficulty in jacketing insulated pipe comes at turns and bends, such as elbows of 90.degree. or bends of greater or lesser angles, for instance, 45.degree. bends, in both long and short radius turns.
As far as is known, the insulating industry presently employs pressed fittings for insulated elbows from 1/2" to 12" I.P.S. (iron pipe size) with a total pipe and insulation O.D. (outside diameter) of 17" and smaller, and "gore" type ells for all larger size bends. The pressed fittings are made in two precision formed matching halves by press molding a piece of sheet metal in the desired size mold to obtain a half elbow. For example, a sheet of aluminum 0.24" thick is laid over the female mold half and the male mold half is pressed into the cavity forming a half elbow approximately 0.016" thick. Two halves are placed over the insulation at the turn and are held in place while sheet metal screws join the halves together along both the inside and outside seams. This procedure suffers from the disadvantages of requiring the use of temporary fasteners to hold it in place, many additional fasteners for permanent securement, putting a seam along the outside bend which is the most vulnerable point of weatherproofing and is expensive and inconvenient in shipping and storage.
For the larger pipe sizes, a "gore" type jacket is either laid out in the field or manufactured in segments to cover and weatherproof the insulation. In "gore" type jacketing, strips of sheet metal are cut out which are wider at their center sections and narrower toward the ends with a slight outward flaring at the ends and are successively wrapped around the insulated pipe bend and fastened together at the inside bend where the two ends meet, usually by a sheet metal screw, until the bend is covered. These "gore" type strips must be temporarily secured so that after the installation of the numerous strips, each strip can be adjusted to provide the necessary watershed capabilities prior to the permanent securement of the strips. The circumferential joints between strips are caulked with a weatherproofing material. The cutting (in manufacture or field layout) of strips for "gore" type jacketing elbows and fastening of individual strips requires more labor and, thus, the cost of such installations is more than 3 times that of pressed fittings for similar size insulated pipe and is the only known method for jacketing pipe and insulation having O.D. measurements over 17".
In my previously filed application, there is described a one-piece metal jacket for insulated pipe bends having a curved metal spine longitudinally covering the curved portion of the insulated pipe bend having the largest radius, and having extending transversely from the metal spine a plurality of opposed paired ribs or fingers of a width such that they are immediately adjacent to each other and tapering outwardly from the spine in a manner to cover the insulated pipe and slightly overlap adjacent ribs or fingers in weatherproofing fashion, the ribs or fingers extending from the metal spine around the insulated pipe and each rib or finger having sufficient length to meet and overlap the end of its paired counterpart, meeting at the curved portion of the insulated bend having the shortest radius, with means such as mechanical fasteners to hold the ends together. Although such one-piece metal jackets are far superior to the previously known multi-piece metal jackets, it is always desirable to make improvements in design or installation or fitness for use. The present invention provides better weatherproofing at the jointure of the metal spine and the fingers, provides improved overlapping along the sides of adjacent fingers and provides better variability for joining the ends of oppositely paired fingers.